hoffman



June 12, 1934. F. D. HOFFMAN DOMESTIC STOKER Filed Aug. 9, 1930 3 Sheets-Sheet 2 @20 ZJG. -Z

u IN V EN TO R /Pf faffMA/v ATTORN EYS F. D. HOFFMAN DOMESTIC sToKER June l2, 1934.

Filed Aug. 9, 1930 3 Sheets-Sheet 5 Mwwfw ATTORNEYS Patented June 12, 1934 parte DOMESTIC STOKER Fred D. Hoffman, Cleveland, Ghia, assgnor, by ,M

mesne assignments, to Hugh J. Monson, Cleve- 4 land, Ohio, trustee Application August 9, 1930, Serial No. 474,247.

12 Claims.

My invention relates to a fuel stoker for use in connection with furnaces or other types of heating equipment and, particularly, to a fuel Stoker of the over-feed type for use in connection with a domestic hot air furnace or other domestic heating equipment, the stoker being so designed as to feed the fuel through the feed door normally provided and being such as to feed the coal over the entire fire area without having the delO livery end of the stoker extending to or over the center of the fire box.

In stokers for domestic heating equipment such as a furnace, much difliculty has heretofore been experienced due to the delivery end of the stoker extending to or over the center of the lire box whereby the fuel, in most instances coal, dropped into the fire box pyramids up to the delivery end of the stoker and, with a Very hot fire, the end of the stoker is burned or otherwise damaged.

Further difficulty has been experienced with stokers of this type due to the fact that no means has been provided for delivering air to the ire zone in such manner that the air and the gases distilled from the burning fuel would be properly mixed so that complete combustion might take place. In other words, the air has heretofore been so delivered that the mixture of gases and air followed a direct path through the re box to and out of the stack. This resulted in a large amount of waste of both fuel and heat. Still further, it is a well known fact that a re bed is built up to approximately the level of the bottom of the fire door before the heating unit reaches the point of highest efficiency and it is desirable that some means be provided for agitating the fire bed sumciently to cause the ash and other incombustible residue to pass downwardly through the re bed and out of the fire box by way of the grates. Such agitation is also desirable in order to keep the iire bed spongy or in such condition that air will have free access or contact with the fuel.

The objects of my invention are to provide an over-feed fuel stoker for domestic equipment wherein means are provided for preventing the fuel from piling up or pyramiding to the delivery end of the Stoker whereby the danger of the stoker becoming damaged by the fire box fire due to close proximity therewith is practically eliminated; to provide a device at the delivery end of the stoker for spreading the' fuel delivered therefrom and agitating the fuel bed so as to cause ash and uncombustible residue to work down through the fuel bed and then through the grates. Thus the fuel bed is kept spongy and oxygen is permitted to have free contact with the fuel; to provide a stoker that may be readily moved to and from the heating unit and will feed fuel through the feed door normally provided; and to provide a means for conducting a supply of air to the fire zone Via the stoker in. such manner as to create a cyclonic or turbulent action of the air and distilled gases to promote complete combustion.

Various other objects and advantageous features may be seen in the followingdescription and one embodiment thereof may be seen in the accompanying drawings wherein similar characters of reference designate corresponding parts, and wherein:

Fig. l is a view partly in elevation and partly in section showing a fuel stoker constructed in accordance with my invention in combination with a furnace which is more or less diagrammatically shown; Fig. 2 is an elevation showing 7a the operating parts of the fuel stoker; Fig. 3 is a view taken on the line 3 3 of Fig. 2; Fig. 4 is a View taken on the line 4 4 of Fig. 2; Fig'.

5 is a view taken on the line 5 5 of Fig. 2; Fig.

6 is an elevational View of the delivery end of s@ the stoker; Fig. 7 is a view showing the power unit for operating the stoker and the means for controlling the supply of air thereto and to the lire box taken on the line 7 7 of Fig. 2; Fig. 8. is a top plan View showing the means for reciprocating the fuel feeding and fuel spreading means; Fig. 9 is a side view of the part of the apparatus shown in Fig. 8; Fig. 10 is a sectional view taken on the line 10-10 of Fig. 9; and Fig., 11 is an elevation of the fuel crusher plate.

Referring to the drawings and particularly Fig. 1 thereof, I have shown one embodiment' of my invention as comprising a fuel feeding stoker embodying a fuel hopper 1 for receiving. a supply of fuel, a conduit 2 extending outwardly from the apparatus, and suitable operating mechanism all mounted on a frame 3 that consists of a plurality of legs with traction elements 4 thereon, whereby the apparatus may be moved towards or away from a heating unit, the delivery end of the conduit 2 extending through the normal fuel feeding opening 5 of a heating unit that is more or less diagrammatically shown and consists of an outer casing 6, a fire box '7, and an ash pit 8 that is provided with ash removers 9 operable by a series of links and levers 10 extending outwardly and upwardly from the heating unit and connected to the operating parts so as to be automatically operated with the rest of the apparatus.

As shown, the delivery end of the conduit 2 is adjacent one side of the fire box 7 and the conduit is provided with a member 11 adapted to fit within the normal fuel feeding opening 5 and adjustable along the conduit to regulate the position of the delivery end of the conduit with relation to the side of the fire box, such member being held in adjusted position by means of a sleeve 12 and a clamping band 13.

The delivery conduit 2, which as a whole provides a means for delivering both fuel and air to the fire area, consists of a steel or iron shell or outer casing surrounding a fuel feeding ccnduit 14, the outer shell or casing serving the purpose of conducting a forced air supply to the fire area and being secured to the rearward portion of the apparatus as at 15 with the fuel feeding conduit 14 contained therein in alinement with a receptacle 16 in which the hopper 1 is adapted to be secured and the outer shell or casing in alinement with a space 17 formed by a part of the hopper base and to which a fan 18 is connected, the space serving as an air supply conduit.

The fuel supply conduit 14 contains a fuel pushing ram 19 that has a flat toothed upper surface for a portion of its length and is circularly toothed for the remainder thereof and which extends from a point adjacent the rearward edge of the fuel receptacle 16 to the outermost or delivery end of the fuel conduit 14 whereby the flat toothed upper surface within the receptacle 16 will cooperate with a fuel Crusher plate 20 located in the receptacle and adjustable by means of a slot 29 to vary the size of the opening into the conduit 14 to first break fuel up into relatively small parts and then deliver the fuel to the re area.

Fuel travelling through the delivery pipe 14 under the influence of the fuel pushing ram 19 will fall down onto the fire area adjacent the side of the fire box '7 since the delivery end of the' conduit extends only to the side of the fire box and will eventually pyramid or pile up until the fuel reaches the delivery end of the conduit. This is undesirable in that burning fuel adjacent the delivery end of the conduit will cause the conduit to be injured and possibly rendered inoperative due to the intense heat. To offset this, a fuel spreading ram 21 is mounted for reciprocation within the outer shell or casing of the conduit adjacent one end thereof, the fuel spreading rain consisting of a hollow casting that is substantially semi-circular in form and has a reduced portion 22 extending within the outer shell or casing and from which it constantly receives a supply of air from the conduit, the air finally being delivered through openings 23 in the enlarged portion of the pusher and to the fire area.' Such air serves both the purpose of aiding combustion of the fuel within the re box and also serves to prevent the heat in the fire Zone from damaging the pusher.

Fuel delivery from the conduit 14 is caused by reciprocal travel of the ram 19 as hereinbefore described and the fuel spreading action is caused by reciprocal travel of Vthe fuel spreading ram 21, the reciprocal travel of the fuel spreading ram being in such synchrcnism with the reciprocation of the rain 19 that the fuel spreading action takes place only during the time of the withdrawal of the fuel pushing ram 19 into the conduit 14. Thus, feeding of fuel onto the fuel spreading ram 21 when the pusher is in its outer position shown by the dotted lines in Fig. 1, which might eventually cause the fuel spreading ram to become covered with coke whereby it would bind or stick, is prevented.

As shown in Figs. 1, 3 and 9, both the ram 19 and the fuel spreading ram 21 are provided with rods 24 and 25 that may or may not form an integral part thereof which extend rearwardly through uprights or guides 26 mounted on the frame and are connected to a mechanism for reciprocating the fuel feeding ram and fuel spreading ram in the synchronism hereinbefore mentioned, the mechanism being driven by a motor unit 27 through the medium of a belt 23 and a pulley 29 mounted on a shaft 30. The shaft 30 carries a worm 31 that is in meshing relation with a worm gear 32 which is disposed on a vertically extending shaft 33.

A driving crank 34 is rigidly mounted on the uppermost end of the shaft 33 and embodies two radially extending arms, one of these arms carrying a relatively long downwardly extending pin 35 and the other arm carrying a relatively short downwardly extending pin 35. The crank also carries an upwardly extending eccentrically disposed pin 37 that has its uppermost end disposed within a sliding member 38 that reciprccates within a guide 33 mounted on the rod 24 that extends rearwardly from the ram 19 and is angularly disposed with relation thereto. With this construction, rotation of the crank 34 in a counter clockwise direction and movement of the eccentrically disposed pin 3*? in an orbital path will cause reciprocation of the ram 19 in a well known manner.

Rotation of the crank 34 in a counter clockwise direction through the mechanism hereinbefore described will cause reciprocation of the pusher or fuel spreader 21 in synchronism with that portion of the movement of the ram 19 which causes the withdrawal of the ram 19 into the delivery conduit 14 by reason of the pin 35 contacting with a laterally extending cross member 39 that travels on guides 40 on the vframe and to which the rod 25 is connected. It will be ap- '5' parent from Figs. 8 and 9 of the drawings that the arms vof the crank are so disposed that the pin 35 will contact with the laterally extending member 39 and move the pusher or fuel spreader forwardly as the ram 19 is moved rearwardly and L? back into the fuel delivery conduit 14. Also, it will be apparent that the relatively short pin 36 will pass over the member 39 and will contact with another laterally extending member 41 that also travels on one of the guides 40 and which is moved forwardly by the forward movement of the pusher 21 at the instant that the ram 19 begins its outward movement to deliver fuel to the fire area, the member 41 being so disposed that the pin 35 will pass in front of such member when the 'crank' is completing its full cycie of movement. The members 39 and 41 are connected together by a sleeve 4i)a and move together as a unit. Thus, the fuel spreading ram 21 is reciprocated during the time that the ram 19 is withdrawn into the fuel delivery conduit 14.

In the operationof this apparatus, fuel fromY a fuel supply placed in the hopper 1 moves downwardly by gravity into the receptacle 16 whose inner walls converge downwardly, such move- :if

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of the ram 19 and particularly by an upstanding dog 44 carried by the ram 19 and which is adjustable to vary the load against the fuel crusher plate 20 which is also adjustable to vary the size of the feed opening into the fuel delivery conduit 14, whereupon the fuel is broken up into relatively small parts and delivered finally to the fire area.

As shown in Figs. 1 to 7, the fan 18 is driven directly by the motor 27 and forces a draft of air upwardly through the space 17 and thence outwardly through the outer shell of the conduit 2 and then to the lire area to promote combustion in the nre box by creating a turbulence in the distilling gases from the fuel and cause the gases to mix with the incoming air, a part of which is delivered to the heating unit below the re area by means of a conduit 45 leading directly from the fan, whereby the gases and air may be completely converted into heat through combustion. rlhe draft of air traveling through the conduit 2 tends to keep the fuel pipe 14 and the conduit as a whole relatively cool and nally reaches the fire area through a plate 46 that covers the delivery end of the conduit with the exception of that portion through which fuel is ejected and that portion in which the pusher or fuel spreader reciprocates. Such plate is provided with slots 47 which cause the air to travel into the fire area in several currents instead of in a single steady stream at one point.

It has been found to be undesirable to force air into a fire area in any form of steady stream. Therefore, a damper 48 having a counterweight 48 that normally tends to move the damper to closed position is disposed over the intake side of the fan 18 and is normally moved intermittently to open and closed position by means of a link connection 49 with the rod 25 that forms a part of the reciprocating fuel spreader. This link connection is such that the damper is open to admit air to the fan during the movement of the spreader forwardly into the furnace and the movement of the fuel feeding ram 19 rearwardly away from the furnace whereby a supp`y of fuel and a puff of air are simultaneously delivered to the fire zone. The arrangement is such that when the fuel spreading ram is withdrawn the damper is in closed position.

Referring to the drawings and the preceding description, it will be seen that I have provided a stoker for feeding fuel to a heating unit that embodies numerous novel and advantageous features. One of these features resides in the fact that means have been provided for intermittently delivering fuel to a re box from a fuel supply and intermittently spreading the fuel over the nre area, such spreading action taking place at a time when no fuel is being delivered. It will also be seen that the fuel feeding ram is given a continuous reciprocatory movement While the fuel spreading ram is given an intermittent reciprocatory movement, the motion of the fuel spreading ram being relatively fast with respect to the fuel feeding ram. With the parts in the position shown in Fig. 8, the shaft 33 is rotated in a counter clockwise direction. The pin 35 moves through a little more than 90 before it engages the member 39. At this time the fuel feeding ram is beginning its return stroke. Movement of the pin 35 180 from the position shown in Fig. 8 moves the fuel spreading ram to its maximum distance in the furnace. At this time the fuel feeding ram has reached the limit of its re- During the next 90 movement of the crank 34 the pin 36 engages the member `41 and returns the fuel spreading ram to its rearward position. During the next 90 movement of the crank 34 the fuel feeding ram will be moved to its extreme limit of movement forwardly or into the furnace. In other words, the fuel spreading ram is at restduring approximately 190 movement of the crank and it is moved forward and backward during approximately 170 movement of the crank. Another featureresides in the fact that means have been provided for delivering air under forced draft into the re Zone in the form of intermittent puffs. This has the advantage of creating a turbulence or cyclonic action of the gases within the fire box whereby the gases will be completely mixed with the air and transformed into heat through combustion instead of traveling in a direct path through the fire Zone to the stack.

What I claim is:

1. A device of the class described, comprising a fuel supply means, a delivery conduit, means comprising a reciprocating ram in said conduit for delivering fuel from said supply means to a fire area through said conduit, means for spreading the delivered fuel over the fire area, said last named means embodying a reciprocating member adjacent the delivery end of said conduit and below the ppint of delivery of said fuel, and means for reciprocating said member in synchronis'm with the half-cycle of reciprocation of the ram that causes the rams withdrawal back into the fuel supply conduit.

2. Apparatus of the class described, comprising fuel supply means, a fuel delivery conduit, a reciprocating ram in said conduit for causing the travel of fuel therethrough, an air supply conduit, means for breaking up the air delivered from said air conduit into a plurality of streams, means for spreading the fuel over the fire area, said last named means comprising a reciprocating member below the point of delivery of said fuel, and means for reciprocating Said member in synchronism with the half-cycle of reciprocation of the ram that causes the rams withdrawal back into the fuel supply conduit.

3. A mechanical stoker for furnaces comprising a base member, a conduit supported at one end by and extending horizontally from said base member, a second conduit within said first conduit, a hopper delivering fuel into said second conduit, means for delivering fuel through said second conduit, a reciprocatory member in said rst conduit disposed below said second conduit, a ram connected with the outer end of said reciprocatory member, means for operating said reciprocatory member to project said ram beyond the other end of said first conduit, and means for delivering a draft of air through said first conduit and through said ram.

4. A mechanical Stoker for furnaces comprising a base member, a conduit extending from said base member, a second conduit adjacent said first conduit and disposed above said first conduit, a hopper delivering fuel into said second conduit, means for delivering fuel through said second conduit, a reciprocatory member in said first conduit, a ram connected with the outer end of said reciprocatory member, means for operating said reciprocatory member to project said ram beyond the delivery end of said first conduit, and means for delivering a draft of air through said first conduit and through said ram.

5. In an overfeed stoker of the class described, the combination of a fire box having a fuel feeding opening in its side wall, a fuel supply means, a fuel delivery conduit extending into said opening, means for delivering fuel from said supply means through said conduit into said rebox, means for spreading the fuel in the rebox comprising a reciprocatory fuel spreading ram mounted in said opening and disposed immediately below the point of delivery of the fuel, means for reciprocating said fuel spreading ram, said ram having one or more openings therethrough, and means for delivering a forced draft therethrough.

6. In an overfeed stoker of the class described, the combination of a iirebox having a fuel feeding opening in its side Wall, a fuel delivery conduit extending into said opening, means for delivering fuel through said conduit into said firebox, said means comp-rising a reciprocatory fuel feeding ram movable towards and away from the fire area, means for spreading the fuel in the rebox comprising a reciprocatory fuel'spreading ram mounted in said opening and disposed immediately below the point of delivery of the fuel, means for imparting a continuous reciprocatory movement to the fuel feeding ram and for imparting an intermittent reciprocatory movement to the fuel spreading ram. f

7. In an overfeed stoker of the character described, the combination of a Firebox having a fuel feeding opening in its side wall, a fuel deli ery conduit extending into said opening, means for feeding fuel through said conduit and into said firebox, a reciprocatory fuel spreading mounted in said opening and arranged to be projected beyond the delivery end of said conduit, said fuel spreading ram being disposed immediately below the point of delivery of the fuel, and means for delivering a forced draft of air through said conduit while the fuel spreading ram is moving into the rebox to spread the fuel, such spreading action taking place at-a time when no fuel is being delivered by the fuel feeding means.

8. In an overfeed Stoker for furnaces of the character described, the combination ofa firebox having a fuel feeding opening in its side wall, a

reciprocatcry fuel feeding ram extending into said fuel feeding opening for delivering fuel through said opening into said iirebox, a reciprocatory fuel spreading ram mounted in said opening and disposed immediately below the fuel feeding ram, means for imparting a continuous reciprocatory motion to the fuel feeding ram and an intermittent reciprocatory motion to the fuel spreading ram, means for delivering a forced draft of air through the fuel spreading ram, and means for increasing the draft of air delivered through said means for feeding fuel through said conduit into said rebox, a reciprocatory fuel spreading member mounted in said opening and disposed immediately below the point of delivery of the fuel and having one or more openings therethrough, and means for delivering a forced draft of air through said fuel spreading ram.

l0. In. an overfeed sto-ker of the character described, the combination of a iirebox having a fuel feeding opening in its side wall, fuel feeding means extending into said fuel feeding opening for delivering fuel through said opening into said firebox, a reoiprocatory fuel spreading ram mounted in said opening and disposed immediateiy below the point of delivery of the fuel, said fuel spreading ram having one or more holes therethrough, means for imparting a reciprocatory motion to said fuel spreading ram, and means for delivering a forced draft of air through said ram during the fuel spreading operation.

ll. In an overfeed stoker of the character described, the combination of a reboX having a fuel feeding opening in its side wall, fuel feeding means extending into said fuel feeding opening for delivering fuel through said opening into said nrebox, a reciprocatory fuel spreading ram mounted in said openingy and disposed immediately below the fuel feeding means Vand having one or more holes therethrough, means for imparting a reciprocatory motion to said fuel spreading ram, and means for simultaneously delivering a forced draft of air above and below the fire area.

l2. In an overfeed Stoker of the character described, the combination of a nrebox having a fuel feeding opening in its side wall, fuel feeding means extending into said fuel feeding opening for delivering fuel through said opening into said iirebox, a reciprocatory fuel spreading ram mounted in said opening and disposed immediately below the fuel feeding means and having one or more holes therethrough, means for imparting a reciprocatory motion to saidk fuel spreading ram, means for delivering a forced draft of air through said fuel spreading ram during the fuel spreading operation, and means for delivering a forced draft of air below the fire area.

FRED D. HOFFMAN. 

